A deductible is your financial responsibility as it applies to the repair. If you are proven not at fault in the accident, then no deductible will apply (depending on your waiver coverage). If you are at fault in the accident or if there is no other party for the insurance to go after, then you are responsible for your deductible. Your deductible ($250.00, $500.00, $1,000.00, etc.) is your responsibility and is taken off of the final claim amount. Your deductible amount is determined when you buy your insurance.
An example: The total repair amount written by the insurance company is $5,000.00. If your deductible is $500.00, then you are responsible to pay the first $500.00 of damages to the repair shop, and the insurance company is responsible for the remaining $4,500.00. The insurance company will automatically deduct your deductible from their portion of the repair check. If no insurance is involved, or if you've been deemed not at fault (i.e. the claimant), then the deductible does not apply.